its not confined to mares....our gelding nicks our mares hay through the bars on the front of the stable ...but thats not all.
He can pick pockets without people feeling...and things disappear. She nicked the farriers wooden handled knife out of his pocket ..luckily I saw ..he might have had a bit of a problem if he had tried to eat it.!
My warmblood has got the right idea - he'll eat the hay belonging to the horse next door before he eats his own, then he'll still happily be chomping next morning while the horse next door is looking grumpy and hungry
My mare always decides that the blade of grass that my other pony is eating belongs to her. She hasn't worked out that she spends so much time trying to get Marbles blade of grass that she's not getting much herself!!